Jetpack brings a wealth of features to your self-hosted WordPress site as one of the best no-brainer plugins for WordPress there is. One feature I just recently used for the first time was the video hosting and video player. I had a video clip that I just wanted to drag and drop into a blog post like I would an image, but it was a little too big. Fortunately I just uploaded it through WordPress.com, it was magically available in the Media dialog on my self-hosted site, and it worked perfectly.